Analysis of data from ESA’s Rosetta mission continues to yield insights into the nature of cometary ice and organics.
Artist’s impression of a comet. Image credit: DLR / CC-BY 3.0.
Launched in March 2004 and following a ten-year journey across the Solar System, ESA’s Rosetta probe made history in 2014 — it arrived at Comet 67P/Churyumov-Gerasimenko and became the first spacecraft to orbit the nucleus of a comet.
In September 2016, Rosetta softly crash-landed on the comet and brought an intense period of more than two years of continuous investigation to an end.
Rosetta data led to many discoveries about the origin of the cometary material and the processing in our early Solar System.
Among the payload instruments, the Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) instrument obtained fundamental properties of the comet by measuring the gases emanating from its nucleus.
“ROSINA analyzed the various isotopes of atoms such as xenon and rare organic molecules, including sulfur-containing compounds,” explained ROSINA principal investigator Professor Kathrin Altwegg, from the University of Bern in Switzerland.
“Such measurements can reveal where an atom was first synthesized, for example, in a supernova, or in the case of an organic molecule, the temperature and other conditions under which it formed.”
“What we found is amazing: cometary ice is mostly older than the Solar System, having survived its formation as ice,” Professor Altwegg said.
“This means the abundant organics found in the cometary coma are also probably older and therefore as such ‘universal’ — not specific to the Solar System.”
“If comets contributed to the emergence of life on our Earth, similar processes could have happened or could happen elsewhere in the Universe.”
One of Rosetta’s key findings was that less than 1% of Earth’s water came from comet impacts.
“By looking at xenon isotopes we can also quantify how much organics they brought,” Professor Altwegg said.
“The unexpected richness of organics found in the cometary coma together with the results from xenon tell us that comets could have played an important role in sparking life on Earth.”
ROSINA’s analyses of 67P’s coma were supposed to be complemented by ground measurements obtained by the spacecraft’s lander, Philae.
But Philae unexpectedly bounced on impact when its thruster did not fire and two harpoons failed to anchor it to the surface. Eventually, Philae lost power and the ability to communicate with Earth.
“We are missing the ground truth, as, due to the hopping of the lander Philae, the two mass spectrometers on Philae could not measure in their nominal modes. Future missions that successfully land on a comet and take extended surface and subsurface measurements would help reveal what the real pristine material looks like,” Professor Altwegg said.
She presented the results yesterday at the AVS 64th Annual International Symposium and Exhibition in Tampa, Florida.
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Kathrin Altwegg. 2017. ROSINA/Rosetta: Exploring the Origin of our Solar System with Mass Spectrometry in Space. AVS 64th Annual International Symposium and Exhibition, paper VT+MN-MoM-8
